Learn to program hardware with a $5 Raspberry Pi Zero and $8 in parts

Eric Thompson

LowVoltageLabs.com

Programming Hardware

  • Why Hardware?
  • Raspberry Pi Zero overview
  • Software setup
  • Programming using Python
  • Basic Output > LEDs
  • Basic Input < push button
  • More outputs and inputs

Why hardware?

Connect to the outside world

Raspberry Pi Zero $5

  • 1GHz, Single-core CPU
  • 512MB RAM
  • Mini-HDMI port
  • Micro-USB OTG port
  • Micro-USB power
  • HAT-compatible 40-pin header
  • Composite video and reset headers
  • CSI camera connector 

Software setup

  • Raspberry Pi Zero needs an SD card with an operating system installed on it
  • Raspbian is the Raspberry Pi's foundation’s official supported operating system
     
  • Purchase an SD card with it preinstalled
    OR
  • Download and install yourself:
    https://www.raspberrypi.org/downloads/raspbian/

Programming language

Python

 

Output - LEDs

Dialight

P/N = 564-0300-132F

 

  • Three LEDs
    Red, Yellow, Green
  • 0.1" header spacing
  • Built in resistors

 

Dialight P/N = 564-0300-132F

LED location

Use GPIO6, GPIO19 and GPIO26 to drive the LEDs

GPIO6 = Red

GPIO13 = Yellow

GPIO19 = Green

 

GPIO12 and GPIO16 drive to ground

LEDs

Turn on the LEDs

# Pi Zero Programming hardware

from gpiozero import *

# Set LED pins to ground
ground12 = OutputDevice(12,True,False)
ground16 = OutputDevice(16,True,False)

# Setup traffic lights
lights = TrafficLights(6,13,19)

# Turn on the lights
lights.on()

# Turn just the Red LED on
lights.red.on()
lights.amber.off()
lights.green.off()

Input - Push Button

Manufacture = ALPS

P/N = SKHHBYA010

 

  • Momentary push button
  • SPST
  • 0.1" spacing - sort of?

 

Installing the push button

Installing the push button

 Top                                                     Bottom

Reading the push button

# Pi Zero Programming hardware

from gpiozero import *

#Set push button input to ground
ground17 = OutputDevice(17,True,False)

# setup the button press 
def buttonpress():
    print("Button press")

#Setup the button press
button = Button(4)
button.when_pressed = buttonpress

Push button and LED

More inputs and outputs

Output - Buzzer

Manufacture = CUI

P/N = CST-931AP

  • Works from 3.3V
  • 0.1" pin spacing

 

Input slide switch

 

Manufacture = Apem

P/N = MS22R

  • Right angle
  • 0.1" pin spacing

 

Input slide switch

Reading the Slide Switch

# Pi Zero Programming hardware

from gpiozero import *

# Set slide switch to high
high24 = OutputDevice(24,True,True)

# Setup Input slide on pin 23
slide1 = InputDevice(23,True)

# Check slide switch
if slide1.is_active:
    print("slide switch right")

Input temperature

Manufacture = Maxim Integrated

P/N = MAX31820MCR+

  • Only requires power and 1-wire interface
  • TO-92 package
  • Standard DS1820 part

 

Input Temperature sensor

  • GPIO27 will be ground
  • GPIO22 data pin
  • 4.7K resistor from GPIO22 to +3.3V
  • Programming

 

Input Photocell

  • +3.3V to one side
  • Other side to GPIO3
  • 0.1uF capacitor
    GPIO3 to GND

Photocell Programming

  • Set GPIO3 to output and low
  • Switch GPIO3 to an input
  • Measure time before GPIO3 input is high

Part Prices

Part Qty = 1 price Qty = 25 price
3 stack LEDs $3.28 $2.15
Push button $0.15 $0.15
Buzzer $1.34 $0.93
Slide switch $0.89 $0.84
Temperature sensor $1.30 $1.24
Photo sensor $0.95 $0.86
                        Total =  $7.91 $6.17

Questions?

 

See me for a free 

GPIO Plus reference board

 

 

Eric Thompson

@LowVoltageLabs

LowVoltageLabs.com

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